Specific capacity is a quantity that which a water well can produce per unit of drawdown. It is normally obtained from a step drawdown test. Specific capacity is expressed as:
where
- is the specific capacity (m²/day or USgal/day/ft)
- is the pumping rate (m³/day or USgal/day), and
- is the drawdown (m or ft)
The specific capacity of a well is also a function of the pumping rate it is determined at. Due to non-linear well losses the specific capacity will decrease with higher pumping rates. This complication makes the absolute value of specific capacity of little use; though it is useful for comparing the efficiency of the same well through time (e.g., to see if the well requires rehabilitation).
Read more about this topic: Well Test
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—Herbert Spencer (1820–1903)
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—John Dewey (1859–1952)